[Pendragon]

aerohead,

Windshield wipers tend to be in a high pressure region at the base of the windshield which is less affected by airflow than other areas, but there is anecdotal evidence of windshield wipers lifting at speed. It just all depends. Hiding them under the lip of the hood became popular some years ago for styling reasons as much as anything. (A Ferrari abused by the lads of Top Gear had to have the springs on the windshield wipers replaced with upgraded ones to keep the windshield wipers from lifting at undisclosed speeds.)

You may recall that "cold air induction" systems used to be located at the base of the windshield of a number of cars to take advantage of the pressure there. Most NASCAR Sprint Cup Cars still have the inlet to the air cleaner located there for that reason.

Nevertheless, attention to small details will be useful as the windshields are increasingly laid back to improve the airflow IMO.

Peter Brock designed the body for the Daytona Coupe for 'Shel. He was interviewed for a recent documentary about it and explained that he based the design on a combination of intuition and information from aircraft aerodynamics, specifically attempting to utilize the shape of a laminar flow wing profile on the roofline which resulted in the highest point of the roof being further aft than on many contemporary car designs. (Who can forget the Gurney bump in the roof?) They did some tuft testing and so on to refine the shape and rushed to get the cars built in time for the racing season. At the track one of the drivers (I can not remember just who at the moment) told them that the car was undriveable and would kill someone unless changes were made. There was some sheet metal available and so the "spoiler" was fabricated and the car taken out again. Upon returning to the pits he suggested taking off "about an inch" which was done and the car was raced that way.

Complications arose when the additional bodies were being manufactured because the constructor took liberties with the dimensions when converting them from standard English (SAE) measurements to metric measurements to which they were accustomed. It took some doing to correct the situation.

By today's standards the Daytona Coupe is probably crude, but the tuft testing showed that it worked and the performance was distinctly better than the open car (20+ MPH on straights).

Anyway, getting to the actual reason I was actually posting back, I was not intimating in any way that the wind tunnel video in commercials was "doctored", simply that they chose a position of the smoke wand that gave a nice, smooth image. They all do it.

Cheers